In the field of gas turbine engines, it may be important to closely monitor and accurately measure the torque output of the engine to understand engine performance and health. By closely monitoring output torque values, potential problems can be identified before they occur. For instance, lower than expected torque output can be indicative of sub-optimal engine operation. In addition, output torque values can be used to estimate the life and/or maintenance cycle of various engine components. Real time measurement of output torque values can permit the estimations of the life of an engine component which can be repeatedly updated and revised. Moreover, real time measurement of output torque can be used to guarantee that the required output power is available at any given time.
Measurements of torque are only useful to the degree that they can be considered accurate. Current methods for measuring torque can be limited in their ability to consistently gather accurate information from a rotating shaft. For instance, some systems rely on reluctance sensors to monitor shaft rotation. Such systems can use rotational readings to estimate shaft strain generated at the shaft away from the sensor location. However, by relying on rotational readings alone, relevant information on strain (e.g., thermal strain) can be lost. For instance, existing systems may fail to account for or evaluate the thermal environment at a relevant strain location. This can lead to inaccurate torque measurements.
Other systems can detect shaft strain in order to determine torque. However, these systems may provide only a single signal path for such measurements. If any point along the single path is interrupted, measurements might be lost or compromised. Merely duplicating a single path system may lead to interference and/or conflicting measurements between the duplicated systems. Therefore, existing systems can often be at risk for failing to provide accurate or reliable measurements of torque.
Moreover, existing strain-based sensing systems can require regular service to provide accurate strain measurements due to, for instance, the effects of long term drift or reliability of these systems. Operation of the measured part or apparatus may lead to deviations from the calibration and require recalibration of the sensing system. In the case of a gas turbine engine, the maintenance required for calibration or recalibration can be prohibitively time consuming, repetitive, and/or expensive.